Crossbelt magnetic separator



April 1, 1952 K. A. BLIND CROSSBELT MAGNETIC SEPARATOR Filed Dec. 5.1947 3 Sheets-Sheet 1 197701NEV151 Ap l, 1952 K. A. BLIND CROSSBELTMAGNETIC SEPARATOR 5 Sheets-Sheet 2 Filed Dec. 5, 1947 INVENTOR. a

April 1, 1952 K. A. BLIND CROSSBELT MAGNETIC SEPARATOR 3 Sheets-Sheet 3Filed Dec. 5, 1947 10 I INVENTOR. BY Q.

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Patented Apr. 1, 1952 CRO-SSBELT MAGNETIC SEPARATOR Karl A. Blind,Thiensville, Wis., assignor to Dings Magnetic Separator 00., Milwaukee,Wis., a corporation of Wisconsin Application December 3, 1947, SerialNo. 789,497

3 Claims. 1

My present invention relates in general to improvements in the magneticseparation art, and relates more specifically to various improvements inthe construction and operation of equipment for effecting separation ofmagnetic particles from a mixture of magnetic and non-magnetic granularmaterials while such mixture is advancing through one or more fields ofmagnetic influence.

The principal object of the present invention is to provide improvementsin magnetic separators of the general type forming the subject of mycopending application Serial No. 747,229, filed May 10, 1947, wherebythe efficiency and capacity of such separators may be augmented.

In my prior application above identified, I have shown'and described animproved cross-belt type of magnetic separator having a main conveyorfor transporting mixed magnetic and non-magnetic granular material alonga definite path, a transversely movable auxiliary conveyor disposedsomewhat above and spanning the said path, a pair of lower and uppercomplementary zone poles disposed beneath and above the main andauxiliary conveyors respectively, and means for energizing the zonepoles so as to create a field of magnetic influence at the gap betweenthe conveyorssufiiciently intense to separate magnetic particlesfrom thebulk mixture and to suspend these particles from the advancing auxiliaryconveyor. This prior cross-belt separator embodies a lower zone polehaving a smooth fiat face coactting with the underside of a main mixedmaterial conveying belt, and a complementary zone pole coacting with topsurface of an auxiliary magnetic particle removing cross-belt, thelatter zone pole having a, series of parallel wedge faces or ridgestheedges of which are spaced equidistant from the flat face of the lowerpole and extend in the direction of travel of the auxiliary belt. Inaccordance with my prior disclosure, two sets of these speciallyconstructed complementary zone poles were energized by means of a commonpair of coils and were associated with successive advancing portions ofthe main conveyor belt, thus providing two spaced separating zones ormagnetic fields of equal intensity each having a pair of coactingrelatively fixed zone poles composed of material having uniformpermeability throughout.

I have now discovered that the efficiency of such serrated or ridgedzone poles may be materially enhanced by providing ridge tips or edgescomposed of material having higher permeability than that utilized inthe remaining major portions of the poles, thereby causing more of theflux tubes to pass through the air gap remote from the ridge apiece andproviding more uniform distribution of these tubes throughout themagnetic zone thus also augmenting the lifting force. I have also foundthat in order to increase the utility and effectiveness of suchcross-belt sepators and to adapt them for the treatment of materialshaving variable magnetic characteristics. it is desirable to vary thewidth of the air gap between the complementary zone poles; and I havemoreover discovered that more efilcient removal of the magneticparticles may also be accomplished by providing a succession of magneticseparating units disposed along the path of advancement of the mixedmaterial and each having a set of coacting zone poles provided withindependent magnetizing coils, the auxiliary belts of the successiveunits being movable in opposite directions while the belts of alternateunits move in the same direction transversely of the main conveyor path.These several features applied to a cross-belt magnetic separator, havebeen found to materially increase the efficiency, to enhance itsflexibility and adaptability, and to augment its capacity.

It is therefore a more specific object of the present invention toprovide an improved zone pole construction for magnetic separators, andwhich is especially adapted for advantageous embodiment in thecross-belt type of separator.

Another specific object of the invention is to provide an improved zonepole assemblage for magnetic separators wherein the air gap betweencomplementary sets of poles may be readily anlarged or diminished. V

A further specific object of my invention is to provide an improved unitfor cross-belt magnetic separators or the like, wherein a set ofcomplementary zone poles is energized and caused to cooperate with mainand auxiliary material conveyors so as to most effectively separatemagnetic from non-magnetic particles being constantly advanced by theconveyors.

Still another specific object of the invention is to provide an improvedcross-belt magnetic separator assemblage embodying a main conveyor belthaving a succession of independent local interchangeably similarseparating units disposed at spaced intervals therealong and adapted todeliver removed magnetic particles in opposite directions away from thepath of advancement of the bulk material by the .main conveyor.

An additional specific object of the present invention is to providevarious improvements in the construction and operation of cross-beltmagnetic separators whereby highly efficient automatic functioningresults and which may be conveniently adjusted to meet varyingconditions of use.

These and other specific objects and advantages of the invention will beapparent from the following detailed description.

A clear conception of the improved features. and of the mode ofconstructing and operating a typical multi-unit cross-belt magnetic.separator embodying the invention, may be had by referring to thedrawings accompanying and forming a part of this specification whereinlike reference characters designate the same or similar parts in thevarious views.

Fig. 1 is a side elevation of a typical multi-unit cross-belt magneticseparator assemblage embodying features of the. present invention;

Fig; 2' is a top view ofthe multi-unit magnetic separator of Fig. 1',showing the same in action;

Fig. 3 is a somewhat-enlarged end view of the multi-unit cross-beltmagnetic. separator, looking toward the main endless conveyor drive;

Fig.4, is a similarly enlarged transverse crosssection through the samemagnetic separator, takenalong, the line 4-4 of Fig. 1' and'looking inthe 'direction of thearrows; V

'Fig. 5 is a. likewiseenlarged transverse crosssection. through the samemagnetic separator, taken alon the line 5-5 of Fig. 1 and lookinginthedirectionof'the arrows;

Fig. 6. is a further enlarged, transverse crosssection through theassemblage, similar to that offFigr 5, but showing additional improveddetails of construction;

' Fig. 7 is alikewise further enlarged side view of one of theimprovedmagnetic separator units;

Eig.j8 is a still further enlarged fragmentary cross-section through aset of complementary asymmetrical, zone poles, theisection having beentaken. along theline. 8-8 of Fig. 6;

Fig, '9} is. a similar cross-section througha succeeding adjacent set ofthe same type of zone poles; and

Fig. 1-0 isan elevation of a complementary set of symmetrical zone polesembodying the innl i While the invention has been, shown anddescribedherein as being especially advantageously applicable to amultiunit cross-belt magnetic separator having a series ofinterchangeably similarreversely disposed magnet units cooperating witha common main conveyor belt, it is not my desire or intention tounnecessarily limit the scope'or utility of the improved features byvirture. of this restricted embodiment, since some of these features areobviously more generally applicable to other types of magnetassemblages.

Referring to the. drawings, the typical multi- V unitcross-belt magneticseparator, shown therein, comprises in general an elongated rigid framecomposed of'a. pair of laterally spaced parallel 7 channel bars llinterconnected by tie-bolts I2;

bars H, and having an upper stretch or, run for constantly advancing arelatively thin layer I1 of granular material from oneendof the frametoward. the other; amaterialsupply'hopper I8 .mounted upon theframe nearthe feed end of V the conveyor I 4; avariable speed propelling mo-i 'torT9 for the conveyor [4 mounted upon the opposite end of the frame andbeing drivingly' connected to the pulley l6 through reduction gearing26; a low intensity magnetic scalping unit 25 mounted upon the mainframe and cooperating with the bulk material layer I! near the feedhopper l8; and a succession of interchangeably similar but reverselydisposed higher intensity cross-belt magnetic separating units 23,

24 cooperating with the advancing layer H at spaced intervals betweenthe scalper 2| and the the hopper It, the. reduction gearing 20, the

scalping unit 2i, and the separating units 23, 24; The lower stretch orrun of the'main conveyor belt may be supported against excessive saggingby a succession of rollers 25 journal-led in bearings mounted uponthechannel bars H. as shown in Fig. 5; and while the belt carrying pulley:it ismounted in fixed bearings; the opposite end pulley I5 isjournalledinmovable bearings which may be adjusted with the aid oftensioningdevices 26' so as to properlystretch the beltruns; see Figs. 1and 2. Themater'ial supply hopper 18 located at the feed end of theupper run of the main conveyor l4, should be abundantly filled withbull; material consisting of; a mixture, of magnetic and non-magneticparticles, and this hopper i8 should also be adapted-to depositarelativelythin and uniform layer H of the mixed materials upon theconstantly advancing upper run of the main conveyor l4. 7

The main conveyor propelling motor I9 isprefierably of; the variablespeed typeso that th'e convey'or M1 and the layer it of' material restinthereon may be continuously advanced atany selected speed; and theinitial or scalping unit 2] is, preferablyof relatively low intensityelectromagnetic type adapted to promptly separate and remove aconsiderable portion of the highly'mag netic particles embodied in theadvancing layer i l; This initial. unit 211 is shown generally inFigs..1.and 2, .and more .in detail in Fig. 4,.and consists primarilyo'fa top pol'eassembly 28, and a flower beltsupport '27 separatedgby. anair gap through which the layer IT of mixedlmater'ia'ls is advanced bythe main conveyor Mooacting'with thesupport 21; anendless auxiliarycrossrheltlil coacting with. pulleys 3,1 3! and having. a. lower stretchmovabletransyerselyacross themain conveyorl I14 in: a close proximity-tothe upper pole (28,; a. variable. speed electric motor-33. drivinglyassociatediwith the pulley 39 at one-endof the conveyor belt 29; amagnetic particle discharge chute. 34 disposed beneath thelower run. ofthe beltza and below the pulley 3l beyond the main conveyor 14.; andelectric coilsv 35 for energize in the magnets so. as. to. produce an'fiel'd of magneticinfluence at thelair-gap, these coils 35 beinglocated between the lower and upper stretches of the conveyor 'beltzt.The scalping unit, Ell-is. of relatively well known, construction andoperation, and is preferably-located nearthe tion anddisposition, and.each of these individual units comprises alower; pole support v36Lmou'nted upon the mainframe channel bars l'l an'dcarrying Oppositeupright side plates 37, 38 which coact with a top plate 36 to provide amagnetic loop; a lower zone pole 45 having a smooth top face coactingwith the bottom surface of the upper run of the main conveyor I4, andalso having an inclined lower face resting upon the upper surface of anadjusting wedge 4! which in turn rests upon the loop support 36; anupper zone pole 43 spaced vertically from the complementary zone pole toprovide an air gap and being detachably secured to and suspended from amagnetizing core 44 which is carried by the top plate 39 of the loop andis embraced by energizing windings or coils 45; an endless auxiliarycross-belt 46 coacting with upper and lower pulleys 41, 48 journalledfor rotation in bearings carried by the loop frame, the belt 4% having alower stretch movable across the main conveyor I4 in contact with thelower face of the upper, zone pole 43; a variable speed electric motor49 drivingly associated with one of the upper auxiliary belt supportingpulleys 4i; and a magnetic particle discharge chute 5i] suspended fromthe loop beneath the lower stretch of the belt 46 and below the motor 49laterally beyond the main conveyor belt I4.

While all of these cross-be1t units 23, 24 are of identicalconstruction, the successive units are reversed relative to the mainbelt M which passes through the air gaps of all units, so that the lowerruns of the successive cross-belts 46 travel in opposite directions anddeliver separated magnetic particles 5| to successive discharge chutes50 located on opposite sides of the main conveyor l4. Each of thecross-belt propelling motors 49 may be operated at any selected speed,and the vertical width of the air gap in each unit 23, 24 may be variedto suit the operating conditions at the successive separating zones,either by raising or lowering the lower zone pole 40 with the aid of theadjacent supporting wedge 4|, or by replacing the removable upper zonepole 43 with another having greater or lesser height. The lower zonepole 46 of each complementary set is fixed against lateral displacementby means of several guide screws 53 with which compression springs 54coact to constantly urge the pole 40 against the adjoining wedge 4|, andeach of these wedges 4| is adapted to be shifted laterally beneath theadjacent pole 48 to vary the air gap, with the aid of a threaded rod 55coacting with screw threads in the wedge and journalled for rotation inthe adjacent loop support 36, the rod 55 being rotatable by means of ahand wheel 56, see Fig. 6. The wedge 4| of each unit is also providedwith slots 51 as shown in Figs. 6 and 9 for permitting adjustmentwithout interference by the screws 53, and a suitable gage 58 forindicating the degree of adjustment may also be provided.

The upper zone pole 43 of each complementary pair is provided with a gapwidening pole 59 projecting from its material delivery end, and isdetachably secured to the lower end of the adjacent core 44, by means ofscr ws as coacting with flange plates 6| secured to the pole 43. Thewidening poles 59 may be detachably attached to their supporting poles43 by bolts 63 piercing the latter, and by replacing the upper zonepoles 43 with others having different height, the vertical height of theadjacent air gaps may be readily varied. The face of each upper pole 43which coacts with the adjacent cross-belt 46, is preferably of improvedconstruction, and as shown in 'Figs. 8 and 9, the bottom face of eachpole 43 is provided with a series of parallel asymnletrical wedge shapedridges 64 extending thereacross and each having a lower triangular edgeportion 65 formed of magnet material having considerably higher magneticpermeability than the upper portion of the pole. These edge portions 65may be secured to the upper portions of the poles in any suitable manneras by fusion of metals, and.

the gaps between the ridges are preferably spanned by angular sectionalstrips 66 of nonmagnetic material welded or otherwise secured to thezone pole 43, so as to provide a smooth and approximately plane bearingsurface for the belt 46, see Figs. 8 and 9.

In the asymmetrical wedge ribbed type of zone pole 43 shown in Figs. 8and 9, the main conveyor belt l4 should always advance through the zoneof magnetic influence in a direction approaching the inclined sides ofthe ridges 64 and away from the perpendicular bounding surfaces thereof,in order to obtain best and most efilcient distribution of the fluxtubes, but the lower face of the upper zone pole 43 may also beadvantageously formed with symmetrical ridges 64' each having a lowertriangular edge portion 65 of material having high magneticpermeability, as illustrated in Fig. 10. These modified ridges 64provided with special lower tip portions 65', also span the zone pole 43and will quite effectively distribute the flux tubes throughout themagnetic field or zone with the conveyor belt travelling therethrough ineither direction, but they are not quite as effective theoretically asthe asymmetrical ridges 64. As in the embodiment of Figs. 8 and 9, thegaps between the modified ridges 64' of Fig. 10, may also be spanned bynon-magnetic strips 66 in order to provide a smooth bearing surface forthe belt 46.

It has been found by actual test, that saturation or high concentrationof magnetic fiux occurs at and near the apices of the ridges of the polepieces 43, and it is well known that if a magnetic circuit is saturatedbeyond approximately 22,000 gausses, additional magnetomotive force orampere turns will increase the'amount of field in the same proportion asthe added magnetomotive force impressed upon the circuit. In otherwords, the advantage of ferric permeability is lost and the materialnear the tips of the pole ridges could be virtually replaced by air or avacuum. Effective lifting force can be obtained:

only with maximum taper of the flux tubes extending from the upper poletips or ridges to the. lower pole. Any additional amount of flux willtherefore pass through the air gap away from each apex, thus enlargingthe pick-up zone but reducing the field intensity, so that the gradientof the field is materially reduced. The geometrical distribution of thefield will then be equivalent to that of a field existing in the gap ifthe ridge tips were rounded off with a large radius,

but this objection can be eliminated by forming.

and the result is increased attraction or liftingforce.

When the improved cross-belt magnetic separator has been properlyconstructed and assembled as herein described, it may be placed innormal operation by merely supplying the hopper l8 with an abundance ofmixed material, by energizing the magnetcoils .35, 4 5, and byoperating, the electric motors i9, 33, 49 to cause the endless conveyorbelts M, 2,9, 49. to advance in the .di-

rections indicated by the several arrows associated with these belts inthe various views. The continuously advancing relatively thin layer llof the mixture resting upon the upper stretch of the :main conveyor M.will be carriedprogressively past .the scalper unit 2| and past the.series of reversely disposedcross-belt units 23, 24, and the magneticparticles .5! of the'mixture will be automatically separated and removedwhile the residual non-magnetic particles will ultimately be dischargedfrom the end of the main conveyor I4 beneath its propelling motor [9.The scalping unit 2! removes a considerable portion of the highlymagnetic particles 5! and the cross-belt 29 thereof removes theseseparated particles .from the initial separating zone and delivers themby gravity into the discharge chute 34. The sub-- sequent units '23,24., gradually likewise separate and remove more and more of themagnetic particles 5|, and the .belts 46 of these units likewise deliverthe particles 5! to the successive discharge chutesfiiilocated onopposite. sides of the main conveyor belt i 3, so. that very littlevaluable material remains in the. residue discharged at the delivery endof themain conveyor.

The speed of the main conveyor belt i i may be varied to insure maximumcapacity, and the speeds of the auxiliary cross-belts 2s, es. ofsuccessive independent units 21,. it may also be varied independently ofeach other soas to in. sure maximum efficiency. Thentoo, the verticalwidths of the gaps at the several separating zones 'may be quicklyandconveniently varied or adjusted to meet different operatingconditions, either by substituting upper zone poles 43 of different.heights, or by merely moving the wedges M with the aid. of the handwheels 5%, and the latter adjustment may be effected at anyof theseparating fields independently of all others.

It is to be noted that when a wedge M is moved improvements inthe.construction of :magnetic separators whereby the. capacity andefiiciency thereof may be materially enhanced, which may be accuratelyadjusted and manipulated to most effectively treat materials havingdiiierence characteristics. The improved upper zone pole structurehaving ridge tips of high permeability,

makes it possible to. obtain. maximum lifting efiectthroughout theentire separating zones, and the removability of these upper polescombined with the vertical adjustability of the lower zone poles 49.also makes it possible to readily vary the magnitude of the so as. toinsure most efficient separation of the magnetic particles 5i from mixedmaterials having a wide range of characteristics. The provision ofinterchangeably similar cross-belt units 23, 24'not only reduces thecost of construction of the entire separator assemblage to a minimum,but also enables the capacity of the separator to be enlarged ordiminished by merely providing more or, less of these units cooperatingwith a common main conveyor [4; and by making these units 23, 24.independently controllable. it: is posand extending across the majorportion of the interior of said loop but being spaced. from said bottommember, an energizing coil surrounding siblerto obtain most effectiveseparation at each a of: the. successive zones. The reversal. of thesucsaid core within said loop, a main mixedimatecessive units 2.3., '24moreover tends to agitate the particles of the advancing layer I! so asto free the magnetic particles from the non-magnetic material, and byproviding for variation in speed of travel of' the belts I i, 29, 46both the bulk material and the separated particles may be advanced atmaximum speed commensurate with greatest capacity.

While the provision of ridge tips 55 having high magnetic permeabilityis an important feature of my invention, the relative adjustabi-lity oithe zone poles it, 43 so as to vary the intervening gap is alsoimportant. The wedge adjustment permits the lower pole Hi to be raisedor lower without shifting it laterally, since the screws 53 positivelyprevent such lateral shifting and the springs E i always maintaineffective contact between the wedge. 31 and the adjacent. surfaces ofthe pole to and support 36. The non-magnetic strips 63 provide smoothbearing surfaces for the cross-belts 15 without interfering with theeffectiveness of the ridged or serrated pole faces, and the ridges at,st may be formed either asymmetrical as in Figs. 8 and 9, or symmetricalas in Fig. 10 and anydes'ired number of these ridges may be provided.The invention has proven highly successful and satisfactory in actualuse, and while all features have benshown as being applicable tocross-belt separators some of these features are obviously moregenerally applicable to other types of magnetic separators;

It should be understood that it is not desired to limit this inventionto the exact details of construction or to the precisemode. of

the interior of said loop but being spaced from said bottom member,anenergizing coil surroundingsaid core within said loop, a main mixed.material conveyor movable through the space between said core and saidbottom membenan auxiliary magnetic material conveyor also movablethrough said space across and above said main conveyor and beingseparated from the latter. by a magnetic *field gap, an upper magnet llole interposed between said core and said auxiliary conveyor, a lowermagnet pole interposed between said main conveyor and said'bottom.member and having a plane lower surface spaced from andinclined towardand along the upper plane surface of said bottom member, and a'wedge ofmagnetic materialcoacting with said plane. reiativelyrinclined surfacesand being adjustable longitudinally of said bottom member to vary thesize of the gap between said conveyors.

2. In a magnetic separator, a continuous magnetic loop having oppositeside members-firmly interconnected by rigid top and bottom members.

a magnetic. core suspended from said top member V rial conveyor movablethrough the space between said core and said bottom member, an auxiliarymagnetic material conveyor also movable through said space across andabove said main conveyor and being separated from the latter by amagnetic field gap, an upper magnet .pole interposed between said coreand said auxiliary conveyor, a lower magnet pole interposed between saidmain conveyor and said bottom member and having a plane lower surfacespaced from and inclined toward and along the upper plane surface ofsaid bottom member, a wedge of magnetic material coacting with saidplane lower pole and bottom member surfaces and extending entirelyacross the lower pole and longitudinally of the bottom member, and ajack screw coacting with a side of said loop and with said wedge for adjusting the latter along said bottom member to vary the size of saidfield gap.

3. In a magnetic separator, a continuous mag netic loop having oppositeside members firmly interconnected by rigid top and bottom members, amagnetic core suspended from said top member and extending across themajor portion of the interior of said loop but being spaced from saidbottom member, an energizing coil surrounding said core within saidloop, a main mixed material conveyor movable through the space betweensaid core and said bottom member, an auxiliary magnet material conveyoralso movable through said space across and above said main conveyor andbeing separated from the latter by a magnetic field gap, an upper magnetpole interposed between said core and said auxiliary conveyor, a

10 lower magnet pole interposed between said main conveyor and saidbottom member and having a plane lower surface spaced from and inclinedtoward and along the upper plane surface of said bottom member, a wedgeof magnetic material coaeting with said plane lower pole and. bottommember surfaces and extending entirely across the lower pole andlongitudinally of the bottom member, a jack screw coacting with a sideof said loop and with said wedge for adjusting the latter along saidbottom member to vary the size of said field gap, and resilient meansfor constantly urging said lower pole and said bottom member intointimate contact with said wedge.

KARL A. BLIND.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 825,672 Mofiatt July 10, 19061,303,397 Rowand May 13, 1919 1,310,802 Manegold July 22, 1919 1,366,979Ulbrich Feb. 1, 1921 1,490,792 Woodworth Apr. 15, 1924 1,522,343 ThomJan. 6, 1925 1,956,760 Forrer May 1, 1934 2,511,484 Stearns June 13,1950 FOREIGN PATENTS Number Country Date 309,950 Great Britain Dec. 12,1929

